Electric discharge apparatus



Nov. 3, 1931. A. A. oswALD ET AL ELECTRIC DISCHARGE APPARATUS Nov. 3, 1931. A. A. oswALD E1' AL. 1,830,210

ELECTRIC l DISCHARGE APPARATUS Filed June 13, 1923 4 Sheets-Sheet 4 /nvenorsf Aff/70H4. @swg/d doh/7 C.' Schw/ew?v of these impulses "is sufficient to maintain the flow of oscillating current. Again, with the high voltage utilized, in the present systems compared withl the relatively low voltage l used inthe earlier systems, the potential differences .across the oscillating circuitconst-v` Y Y desired oscillations,'their presence, for the reasons given above, is detrimental to the proper operation of the system. i

Y .T he present invention provides an arrange-` v ment adapted to be associated with a system comprisinga number of` parallel connected high-power-highfpotential electric discharge devices, which effectively preventsthe pro-l duction of undesired oscillations.

ment isprovided comprisingresistances and reactances adapted to be associated with a v system includinga number of three electrode electric discharge devices having their electrodes' connectedin parallel, constituting'in 11i-,effect an impedance network which provides .afplurality of paths, one ofv which is of low impedance for thev high'vfrequency energy whichfit'is desired 'to reproduce butY offersk l impedanceto current impulses ofun-vv V- desired frequencies, while the Vother path is l offr'elatively low impedance for` oscillations of undesired ,frequencies `and includes meansv `for ,suppressing or vdissipating them, or, at

,'40 least, yfor so lreducing their amplitudes that :gjtli'ey are insufficient to maintain. the flow of oscillating ycurrents of. the undesired fre-H quenciesj potential electricy discharge devices.

Another object isto provide for the divervsion of impulsesof undesired frequencies througha' path associated with a system com- 'y ;.-pr'ising a number of interconnected electricVv discharge devices which includes means for dissipating their energy.

YStillan'other object is to provide anv ar' rangement having a path for currents ofde-i f f,sired-frequency across which a high potential isimpres'sed anda path forundesired Voscilarebeliel besetforth with particularity .in

s e5' nded' cia'ims. Thefinvention itself,

e `One object Vof this invention to provide 45 for the suppression of parasitic oscillations Gin ya svstem which includesVV high power high Y however, both Yas to its organization and method of operation, together with additional objects and advantages thereof, will be best understood by referenceto the following description taken in connection with the accompanying drawingsin which Fig. 1 is a simplified circuit .diagram of an electric discharge system having the invention embodied in the output circuits of the tubes. Fig. 2 showsaa circuit similar to that of Fig. l but ywith' the invention applied to the input circuits of Vthe" discharge-devices. 3 is a circuit similar to that shown in Figs. 1 and `2 in which the invention is illustrated as applied to both the-input and output circuits of a system including a number of electric discharge devices and Fig. l isanrend view of a rack orframe for a system comprising a number .of Velectric discharge devices embodying theinvention. Y

The invention will he hereinafter disclosedV as applied to a radio signaling-system in which they electric discharge devices. are emy v y,ployed to amplify high frequency'carrier 25 According'to this invention, an arrange- I waves which may,y be used either for radio telegraphy korradio telephony. Y t

Y Referringnow to Fig.` 1, there is shown a radio transmitter'y in which the high frequency waves are supplied through a circuit 1 andare impressed upon the common input circuitloften parallel connected high-powerhigh-potential4` amplifiers 2 to 11 inclusive, to supply-thethigh frequency waves in ampliiedV form through a 'transformerrl pro-` inciallic cfore, thev secondary of vI which is'y included in an antenna circuit 13. As shown in this figure, the circuitl is coupledv to the common input circuit ofthe amxplifi'ers by the transformery 14 having one ter-V minal of its secondaryconnected.through a 1 filter 1`5.-with,agpolarizing source 16, the opposite terminal jefthis winding'beingl connected bya-conductorl' and leads 18 to each Y of the gridfor control electrodes of the amplifi'ers. ,Y Connectedin parallel withthe sec- J ondaryy winding of thetransformer 14 is a resistance 14a; which is of such order of magnitude relatively to theinternal inputv imped- 'ance of thedischarge devices, thatthese devices are caused to faithfully repeat the high l frequencycurrent impressed upon their common input circuit substantially withoutdistortion. 'lhe source lserv'es to impress a polarizing potentialY upon the grid electrodes of the amplifierawhilethe filter 15,'is adapt- 1 `ed to 'suppre'ssthe voltage 'variations' of the source 16 sueh'as,-for example, commutatcr ripples, whereby -a constant` polarizing potential willfbe suppliedv tothe control electrodes oftheamplifiers. Alternating cur- 1f rent from the source 19 to heat the filaments is transmittedthroughvthe transformer 20 tothe filament circuit 2l vacrosswhich the l filaments of ,the vramplifiers are connected in parallel. l, Connected across lsecondary 11 Y rasa-f1.6;

Winding `of .'.thestransformeri 2OV are la pair ofy :ondensers' '22,: the adjacent plates fof f which :onductors 21,secondary lof theV transformer 20, ground 23, and thence through ground 28 so the negative terminali of the source 24." The ,conductor-26pm connected?throughr a blocking'V condenser 27A-to the priniarywind` ing of .theftra'nsformer l2having avariabe f condenser connected acrossitito constitute a 3ircuittuned1tothefrequency of the waves to be transmitted.l The tuned circuit is groundedat28. f i f Included in each of the leadsi2i'A connecting. they anode .y of one ampliiier'i tothe .common conductor 26 is a reactive device having parallel'paths,one of which comprises afresistance .29'V and the other an inductancev 30. The

resistance .29 offers highs impedance to Vthe' flowl of high..frequencyxcurrents ofv all fre-. quencies, while the inductance 30 provides -af' low .impedance path for,v the lhigh frequencywaves to be amplified. The resistance 29 and* inductance 30 together vofferresistivey impedj ance tothe -lowrofundesired high frequency current whileV inductance 30-provides a low impedance path for the high frequency waves tobe amplified. rThe combination of thetwo in each r*plate* circuit tends to reduce singing. Their eifectisJtwo-fold, first to reduce theV frequencyy at which singingtends to take place-,this has the effectto reducing the tend-` ency ofl thecircuit to sing,^andsecond, to: in#

crease *the ldamping to-a point Vat `which voscillations willnot be supported'. 'fr

This iigurejserves to diagrammatically il-j lustrate Y the arrangement .andy relative posi tions kof ten amplifiers as they are assembled' on a rack or frame to Aconstitute a bank. The

amplifiers are shown as arranged in two rows" withthe amplifiers' in thetwo rows opposite-v each other. in the same transverseplane. vBy

this method of mounting, it is kpossible to re duce the length of the leadsxc'onnecting the respectiveelectrodes to the-common bus bar and hence -toreduce the inductances of these leads `to a minimum. Asstated above, these inductances are` affactor in Ldetermining the.A

inherentA reactances ofthe system,

Interconnecting `the anodesofthe adj acent amplifiers rin each row is afpath Vincluding* a resistance Interconnecting vtheanodes of the amplifiers 2-and y6 and als'otheV anodes of the amplifiers l7 and 11 areconductivejv paths each including a resistance i# 32." l-Intercon--V necting the anodes ofthe amplifiers Sandra andtheanodes'oftheampliers 8 and l0 `are conductive paths each including. a resistance' 33. Connecting the anodes of the amplifiers 2 and 7,3 and 8,4 and 9,5` and k10, 6 and 11 are conductive paths each including a re.

sistance'34. Each of these resistances 3l, 32,

`33and .34 is 'of the order :of 100 ohms and hence isxadapted to providea relatively low impedance path for oscillating currents of high frequencies. The terminals yof these paths are rconnected to yelectrodes:supplied from thesource #24, so that there is no difference of potential yimpressed upon them except .thatdue to differences in the impedances ofithe'leads connecting thefrespec.- `tive electrodes to lthe comm'onfbus bar 26.

However, the leads 27 yand* included impedance devices29-.3O arecarefully designed to imposeequal impedances to the iiow of the current` toV be amplified` and hence any in- 'equalitiesfin the potential drop across the respective leads due l.to the flow of the/amplified current'willbe caused by differences in thegphysical characteristics of the wire used for this purpose. Since it possible to secure conductors having identical characteristics, it will beapparent that leads 27 of equal impedanceslcan lbe vprovided and, as a result,'that thefsame .potential will be im- Apressedupon-the electrodes of the discharge l ydevices connected by the low impedance paths including the resistan'ces 31 .to 34.

VTheoperation of this system mayjbe de'- scribedas follows: Carrier waves supplied bythe source l are impressed upon the input circuits of the parallel connected amplifiers by the transformerfletand serve to control the flow of current inthe spaceibetween the iilainents and anodes of the ampliers. Space current will flow from one terminal of the lUU source 24, through the choke coil C25, conductor 426, leads j27,.water jackets 27a, contacts 276, tothe anodes 270, across the space 1 between the anodes andfilaments `of the amplifiers, through the Acircuit 21, thesecondary windingo'fzthe transformer 2O to ground 23, and' thence to the grounded terminal 28 of the source 24. High frequency waves, corresponding to those supplied by thesource l, Abut in amplifiedV form, will flowfrom Vthe anodes 27e of the amplifier through the con-y tacts 27?), water jackets 27a, leads 27, inductances 30, conductor `26, condenser 27A, tuned circuit, comprising the primary winding of the transformer'12 and parallel connected condenser, to ground 28 and back through groundy 23 to the filaments of the ampliiiers. These amplified'wa'ves will be impressed upon the antenna"A circuit Y including lthe secondary winding ofthe transformer 12,one terminal of which is Vconnectedto the antenna 13 and theother terminal to ground at 35...'Y f

. The kflow, of :oscillating impulses of undesiredV frequencies throughfthe 'leads 27 to lit the commonconductor 26-is preventedjby the lflrlowever, Veach pairfof plates'con'stituting operation -of the combined 'impedance' dea vice 2li-'30, while ,theY high frequency current of desired.- frequency willtraverse the low impedance Vpath3() 'shunting the 'resistance the setqdescribed above is interconnected-by paths, including the resistances V31 to 34,v across f which thereis no diiiierence of potentialdueto the energy of desired frequency. rilh'ese paths offer. vrelatively low impedance vto oscillations of high frequencies and are in parallel; with thel high impedance paths each including the-,resistance 29 and shuntingin-` ductance 3 0; Undesired oscillations, being prevented, from' traversing ythefhigh impedf- 1 impedance paths including thef`resistances` 3i1to' 34.- The value of theres1stances31 t0 in, the :resistances 31 to'34 inclusive. It will,"V

Y so

coinmonebuszbar.; .Any oscillations .of 11n-.f

c resistances 3119034.- Inother.words,the`imf" duct currents of desired, frequenciesand ValsoQl suppressionmeans. .f

ance paths, will tend to flow through the'iow 34, included in the low impedance paths, is s o chosen'that theldroprof potential betweenV the pairof plates 4connected by each of these paths, because of the undesired oscillations,

. is insuflicient-to maintainlftheir flow.. Asa e result the undesired oscillations'will be suppressed by, or th'eirenergy will be dissipated therefore, be seen'that the impedance devices 29-30 serve `bothftoblockV and suppress f undesired oscillations whichV tend vto `flow tothe desired Vfrequencies due solelyfto interaction between'ithe devices vwill bel yforced, to flow through Ythe suppression paths; including the pedance'` units 29-30 -aie Y adapted to conas'a-means forztrapping currentsl ofundesired` frequencies; and the pathsvincluding the resistances 31.,to .34 constitute additional Y iidditionalr banks ofainplifiers, that describedi-above and including means forsu ressin undesired 'ork arasitic oscil.YV

Vfilter `15. -Hea-ting current for the cathodes ofthe amplifiers isjsupplied-'hy an alternat-v ing 'current source 19 througha transformer 20. Space current is Vsupplied tolthe @ampli-V fiers by thesource 24 through ai choke coil 254 'and' conductor ,26, and theoutputcircuit ofY the ampliiiersiis connecter-itc an antenna-by the conduct'or26` and-transformer..12. Thusfar: this arrangement .isiidentical with that described@,witlitreference to" Fig..1.' ln, this arrangement, however, the parasitic oscillation fsuppressingmeans is included in the inputvcir-cuitof the ampliers.' -V c x The secondarywinding of the input transformer' 14, shunted by a resistance of such` connected resistance l129 Vand inductance 130.. The controlel'ectrodes of adjacent Vpairs of amplifiers in each row Aare connected by a path including a resistance 131. The control electrodesiof the ampliers 2', and 6, and 7 and 11, are interconnected by paths each including va .resistance 132. The control electrodes of the amplifiers 3 and 5, and r8 and 10, are interconnected by paths eachrincluding a resistance 133. `The control 4Aelectrodes of the amplifiers 2 and 7, 3 and 8, 4V and 9, 5 and 10, 6 and 11, are connected by paths each including a resistance 134. As described with reference to the resistances 27 of F ig. 1, the resistances129 offer high impedance to all high frequency currents, whileV they inductances130 constitute low impedance paths, in shunt to the resistances^129, rfor the high frequency Waves which are to be amplified.

.Moreover, the paths including the resistances 131,132, 133 miler are' or 10W impedance 'to-high frequency currents and interconnect 4electrodessupplied with equalpotentials, so 'that no current of the frequency to be amplified flows through the Vpaths including them. v 'Y through the leads connecting the control elecbe amplified will flow through the paths provided by the inductances 130 which, as stated above,fare Vdesigned to offer low impedance' to.V currents of this frequency. Y Undesired oscillating'impulses set up in the system tending to flow to the common bus bar 17 will be suppressed and those due to Areaction be tween the devices will be diverted through the 'paths including fthe resistances131, 132, 133

and'r134. ..However sincel the voltage impressed across each ofthesepaths is in- Vsuiiic'ient toV maintain the flowof' current therethrough, undesired oscillations, .duel toI reaction vbetween the devices,jwill be'sup! pressed. Anf amplifying Vsystem comprising.

a plurality of banks,- similar to that'just described, may be provided by connecting the.

parallelk conectedoutput circuits of the different banlzs to conduct-ors 36,;thei`r 'cathodesg to conductors38, and their commoninput circuits to conductor 37.7"?

F ree or parasitic oscillations developed iny the system will be prevented .fromvcirculating Referring to*A Figi'. 3', there. is shown alradio tranen-litter including any `amplifying system l ini'whichzmeansfor suppressing undesiredl'or paarasitic oscillatibns, similar to'that usedin the preceding figures', is associated with both 'ihe input andoutpu-t circuits of` the amp-li?- This' arrasngement is similar' to that shown in.v the preceding' figures n that thehigh frequency"waves to4 be' ampliied ariey impressed on the input circuit' of .the ampliiyingsystem through the transformer 114. Pol'arizing. po1

tenti'al supplied tofthey controli electrodes. oii L the: amplifiers, threufghi the. Vfilter' 15', by isoureer 16a" ylterriatin 'current or heating Athe cathodes is supplie thereto: by thefsouirce 119? through the# transformer20r VSpace cur'' rent is supplied to the ampliersby'thefsource `24. tlrroug-lt ythe cliche coi1if25, andi `the l am'- phe'd'. high-lv trequeircyf current Vis transmitted through' the conductorr r26', lcondenser1217A an'drtransormer 12' to the antenna circuit 13;l In. this arrangement',thegsccondarywinding ot thefinpuft transformeriifl. is connected to`A the? control electrodes of: the amplifiersl by leads 4U each havingy in series: therewithparalrieli connected resistance 129 'and` inductance 1130:): Each pair of adj acentcontrolleiectrodes Yare eenneeteet by' a patlr including a resist ance 1311.. I The cont-rc1' electrodes :of the amplifiers f2 audit, and. 7 Aand 115i are eeuneeted by paths eaehineludingf a resistance 132i! The control electrodes of the amplifiers anjdf, v and; f8 and 10;? are connected "b1 4paths' eachf includving."a:resistance133?? ejcojntro'lr electrodes or' theamphiers 2' ands?, andf8,}4 and 9, lanolY 10;. and tand 11areconnccted by means n et pathsveach in'cluding-iV af resistance 134.

5 10; 6? 111,/arefconn'ected by paths each. includ-ing a resistance '234. jThe-resstancesf 1129andg229 ofer highinipedance to all high frequency :urrentsl while the-'induc- Y I' pressed across these paths, as described with tances13(7)a1ndJ 230, respectively, connected in shunt" of the: resi stances 12-9? and' 229', are deisigne'di tov ofilerllow impedancelto currents' of thefrequency'to be amplified. rlhe resist` ances 131 to 1234and tov 234, .bei'ngeaclr off4 the; order off 100y ohms, are Toflow ima pedance for high frequency curfrents'- How-L ever. since"r there is substantially' iro potential difference' between the electrodes` interconf nectedi by th'eplO' ohmrgpathsno" high Y'quencycurrentwilhlow between these eleci trodes: y Y Y -Thelfhigh 'frequency Waves supplied through the circuitl will produce a fluctuatingy potential of the same frequency in the secondary windingfoiithe transformer 14 Awhich will' befimpressed'upon the control lelectrodesrof thearnpliers 2 to 10' through c0nductors'17,`leads 4() and inductan'ces 130;

This fluctuating potential will cause the current, supplied by the source 24 through thel inl ductancef25, conductor 26, leads 140 tothe anod'esand thence across the space between pressed upon thecontrol electrodes. In this manner, waves of the desired high frequency,

in amplified form, will be supplied frointhe anodes of the discharge devices through the leads 140, inductances230, conductor 26,-con f 'denser 27A and transformer 12 to ground 28,

thence to the ground connection 23, circuit 21 to the cathodes and Vacross the space; path to the anodes of the devices. The transformer 12' serves to impress thehigh frequency currents upon the antenna circuit 13.-

Oscillating impulses of undesired frequencies produced `in the system, which tend to flow'through the leads 40, will be pre` vented from' reaching the conductor 17 by the resistance 130 and will be suppressed bythe resistance 129'. l Y

ndesired impulses, ydue vto reaction between the' devices, will tend to traverse the low impedance paths lincluding the resistances 131, 132, 133 and 134 interconnecting the" pairs ofc'ontrol electrodes; However,

thesey resistances beingv of proper vvalue and ineach of the plate leads. Undesired oscil-I lations, v due'to interaction between the'vdevices',`will tend to flow ythrough the lowl im# pedance paths including the resistances 231,

232, 233 and 234. However, since the same potential is supplied to the anode's and there is substantially no difference of potential 1in-y reference to Fig. 1, the parasitic oscillations will be'. suppressed by the resistances .231 vto 234. f f Y ,Y

vReferring toy Fig. 4 there is shown an end View ofa panelupon which a bank ofy high potential high voltage ampliers may be mounted. The amplifiers illustrated areof :the water-cooled type having external anodes V1adapted tov be inserted ina chamber through their anodes `cathodes, to fluctuate in accordan'cewith Vthe variable potential `iniico , its

'iis

kwhich maybe caused to circulate water, or

other cooling" medium, Hsupplied from any suitable source, such as, `for eXample,.an ordinar'yfvcity water main. Pipe 41,'-leading from the city water supply system or any other suitable source, is connected by an insulatingv Y conduit 42, such as a rubber hose, to a pipe 43 Branch pipes 44, eachk including an insulating sleeve 45, connects pipe y4 3 to chambers v27a in each of which the anode 2,70 oan amplier isenclosed The water circulating through the 1 chamberf 27a `is discharged through branch pipes 48, each including lan Vinsulating sleeve 49, and the pipe50 tok a pipe 51 connected by'means of a flexible insulating conduit 142 to the pipe 52 which may befconnected to a city sewer main. The iiexible conduits 42 and 142 are wound onpa spool 53 which is adapted to besupportedon the 'panel Vstructure by high tension' insulators 54. The amplifiers aremounted on base plates secured to frames`56 which in turn are secured to the supporting frame by high tensionin sulators 57 f Y y Y The conductors 21 supply heating current to the cathodes of the ampliiers.y Leads 18 serve toconnect the controlk elements of the amplifiers tothe input conductors 17 which are secured tothe supporting frame by a high tension linsulator 58.` Secured vto :the waterjaclets 27a for the anodes 'of the am plifiers is a box 59, herein shown in section, in V'which the resistances 31, k32, 33 and 34'are adapted to be mounted. f It is intended that the parasitic oscillation suppressing means bey included in the plate circuits of the ampliers, and lhence theiresistances enclosed v in the boX 59 will be connected in'suppression paths interconnecting'the anodes of the amplifiers. The ampliier anodes are electrically connected by the spring contact conductors 27?) to the casings 27 c, which arev connected'by theconductors-Gl tothe units 62,

one 'for each amplifier. The units 62 are iny turn connectedte the platefconductor or bus-y bar26.w"V Y Each unit 62 comprisesa pairof resistances 6 5 enclosed in an insulating cylinder 63 having a binding p ost 64 to which the conductor 61 is connected. The binding post 64is confnected to `a short conductive rod extending Vvinwardly.f ofthey cylinderlv to which is conmentindicated in Figs. 1, 2 and 3, respec;

tively. bythe reference numerals v29, 129 `and 229. The external diameter of the lower portion of thev cylinder 63f isreduced, andthe inductance coill is wound upon this reduced portion.r Oney terminal ofv this coil, Y which constitutes the inductance" indicated in Figs. 1, 2 and 3, bythe reference numerals 30, 13.0 and 230, respectively, is connected to the binding post 64, while its other terminali and the bindingpost 67 are connected 4together and to one contact 68 of aknii-eswitch; l The other'contact 69 of the switch is connected to a binding post 70 adapted to be connected to the conductor 26.; The movable switch :blade 71,- provided with a handle 72, is pivotedto the contact 69 and is adapted to engage the contact68, whereby the'anode .of each amplifier may be separately'connected tothe 'commonfbusfbar 26.7` i :fr Y

.. The amplifying system described above is welly adapted for use in any systemwhere low power alternating wave energy is to be'amplified to Aproduce high powerj high` potential energy of; the same wave form.:

A high power radioy transmitter includi ing two amplifier banks, each consisting of ten tubes connected to the transmitting antenna, has been used to :supply energy of ,up wardsl of 150 kilowatts to an antcnnafcircuit. The plate potentialemployed vvasoic the order of k10,000 volts and the frequency of the waves radiated was labout 55,000 cycles.v A normal polarizing 'potential' of betweenV 250 and y300 voltsA wask applied to the control electrodes of theamplifiers.` Associated with eachbanli of amplifiers was a networlrforsuppressing undesired oscillationsi-n which .blocking resistances 29 (229).were of theo'rder of'1200 ohms. Theinductances 30 (23,0) in shunt 'toy the 1200 ohmsresistance elements :,weref..1 millihenry and the resistances included in the paths interconnecting'the electrodes, that is, the resistances 31 to 34 1(231 to 234) were 100 ohms. In the operation of this-arrangement, it was found possible to amplify a modulated carrier wave ofthe'orderv of 55,000 to 58,000 cycles without interference by parasitic -or undesired oscillations. From the preceding description, itV will be seen that this invention is adaptedto provide an arrangement whereby systems-including electric discharge devices-maybe used to sup..

Y plyfan enormous' amount of power` atv high voltage to a load circuit` and are, therefore, well adapted for radio telephonie communication over longfr distancesv Obviously, the est sential `principles of this invention-may be used in association with system including electric discharge devices ladapted to supply high.g-power high potential energy ltoa load circuit and hence the invention Amay be are plied lto discharge devices-operating as-oscillator or` modulators. 5

Certain arrangements and specificv details have'been described above with the sole object of",clearl,yand Completely describingfthe nature fof `this invention. However, as stated above, this invention islof general'application and is not to be limite'dto these arrange- ,l ments or ldetails,`nor bythe theory ofoperation set forth, but l only-,by the scope of the appendedclaims. Y i Y Y Y y -vlllhat is claimed is:

` i In a space'discharge system` including a ing-Waves of'desiredfrequencyto traverse a 'low impedance path therefor, and causingV said undesired oscillationsto traverse a differentimpedance path. x

2. InA a systemrcomprising .Ya-plurality of `Aspace discharge units connected in `parallel toa common output circuit, themethod of preventing the production of undesired oscillations inthe system which comprises causing oscillations Vof desired frequency to trav-A Y* erse a low impedance 'path therefor and exeau cluding oscillationsof undesired frequency from' saidv path by diverting and suppressing saidI undesired oscilla-tions.

3. i In a space vdischarge:system including a ,plurality of parallelconnected spacey dis- @vez Vnecting their corresponding electrodes in pai'-v allel and including separate conductive paths for oscillations of di erent 'frf'iq-uencies` thel charge'iu'nits, .the method? of. `preventing the production of undesired oscillations in the system which coniprisesfcausing oscillations 4of desired frequency totraverseralow impedance path' therefor While excluding oscillations vof undesired frequencies therefrom, and

Vdissipating the undesired Yoscillations by causing them to traverse-ga `conductive path in parallel 'with said first mentioned path.-

-l-L' Ina system including a plurality of parallel connected space discharge units, the

method of--preventing production of undesired roscillations inthe system Which comprises causing oscillations of desired frequency from the respective units to traverse parallel conductive paths While'diverting undesired oscillations fromsaidrp'atha and suppressing said undesired oscillationsn 5; Ina systemconsisting of anuinber kof electric discharge devices havingcircuits coniiecting their lcorresponding.electrodes in parallelfand includingr separate conductive paths for oscillations offdifferent frequencies, the'met'fhod of preventing the production of parasiticoscillations which comprises causing oscillations of desiredfrequency to floiv A through oneof the vconductive paths ivhile excluding parasitic impulses therefrom and suppressing'the parasitic impulses in the associated conductive paths.V

Ina system consisting ,of a number of electric discharge devices having circuits conmethodfof preventing the'productionof undesired` oscillations which comprises causing oscillation of f desired frequency to'y "flow through: one of the conductive pathsl While excluding undesired oscillations therefrom and suppressing` the undesired oscillations in the other path.

7. In a 'system consisting of a number of electric discharge .devices having circuits connecting their coi'respondiiigelectrodes in par-V allel and including separate conductive paths for oscillations of d-ilferent frequencies,v the method of preventing the production of un-y desired oscillations 'which comprises .causing oscillationsl of desiredv frequency to flow through one of the conductive paths While excluding undesired oscillatory impulses therefrom, diverting theiund'esired impulses through .the other associated conductive paths and limiting the electromotive force .impressed acrosst'hepsaid last-meiitioned paths so that the energy of said .impulses is dissipated.

8. In a system consisting of a plurality of Velectric discharge devices having their electrode circuits connected 'iin' parallel and including separate conductive vpaths for oscillations of different frequencies the method of preventing the production of undesired os-y cillations Which comprises causing desired' oscillations to flow through one of said paths While'excluding undesired oscillations therefrom, suppressing undesiredoscillations tending to. traverse this path, diverting other undesired .oscillations through other paths' and suppressing said other undesired oscillations. 9. In a system comprising a number of electric discharge devices having circuits vconnecting their corresponding electrodes in parallel, means'fassociated With onezof said circuits constituting a path oflow impedance for Voscillations of desired frequencies and a path of high impedance for impulses of undesiredk frequencies, and other means associated with said circuits which is Vof low iml pedance for the undesired frequency impulses and is adapted to dissipate the energy of said impulses.

1,10. In a system comprising a number of electric: discharge devices having circuit connecting their corresponding electrodes in parallel,'means associated With one of said circuits'constituting a Vpath of lou7 impedance for oscillations of' desired frequencies and a path of high impedance for impulses of undesired frequencies, other means associated with said circuit which is of lou7 impedance for the undesired frequency impulses, and means for "limiting the electromotive force impressed' across said loiv impedance means whereby the energy of said impulses iswdissipated therein.

11. In a system comprising a number of electric discharge .devices havin g circuits conf iso I' which is offlovv impedance for oscillations of desiredlfrequencies but of high impedance lio for oscillationsY of undesired frequencies and Yincludes means for suppressing undesired oscillations,\vhile the others are of low imped- 'ancefforI other undesired oscillations and include means for suppressing said other undesired oscillations.

vl2.l In acsystem comprising a number of `electric discharge devices having circuitsv connecting their corresponding electrodes in vparallel,"nieans lassociated YWith one of said circuits for blcckingand suppressing undesiredA oscillations but of lovv impedancefor Vdesired oscillations, and means of loW im'- fpedancefer other undesired oscillations in-` cluding means for suppressing said other osi l cillations.

of high impedance for undesired frequency impulses, and other means associated With said circuit which is of lovv impedance for the undesired frequency impulses and is adapted to dissipate the-energy of said impulses. --lll In a system comprising a number of electric discharge devices having grid and plate .circuits respectively connected in .parallel, means associated with said plate circuits ccnstituting a path oflovv impedance for oscillations of desired frequencies and a path of high impedance for undesired frequency impulses, and means included in said last-mentioned path for dissipating the energy of said impulses.

l5. InaV system comprising a number of electric discharge devices connected in parallel andfhavingfgrid and plate circuits, means for supplying current to be amplified to the grid circuit, means for deriving amplified currents from the plate circuit, and an impedance network associated with one of said circuits adapted to provide a low impedance path for said amplified currents and at the saine time a high impedance path forimpulses of undesired frequencies, and a second path of low impedancefor the undesired impulses. v

16. In `a system comprising a number of electric discharge Vdevices connected inparallel and having grid and plate circuits, means for supplycurrents tobe amplified to the grid circuit, means for deriving' amplified currentsfrom the platel circuit, an imped* nance network associated With one of said circuits adapted to provide a low impedance pat-h for said amplified `currents and at the V'same time a high impedance path for impulses of undesired frequencies anda'second path of low impedance for the undesired im'- pulse's, andinean-s include-din said last-men# tioned path. for dissipating the energy of said undesired impulses. i

17. In an amplifying system, thecombination'of a number. of amplifiers connected in parallel having grid andplate circuits, means for supplying current to be amplified to said grid circuit-s, aV common output conductor, connections for supplying amplified current tosaid'conductorfrom the plate of each of vsaid amplifiers. said connections being of low impedance for the amplified current but ofhigli impedance'for,Current impulses of undesired frequencies, and alternating current conductive Vpaths of loW impedance for current impulses of undesired frequencies interconnecting the' plates of said amplifiers.

18. In an amplifiersystem the combination of a number,l of ampliers` connected in parallel having grid and plate circuits, means for supplying current to beampliiied tosaid grid circuits, a common Loutput conductor, connections for supplying amplified current to said conductor including aneleinentwhich is of high impedance for high frequency altern ating current shunted by'an element-oflow impedance for amplified currents of ldesired frequency which is-also of high impedance for alternating current impulses Yof undesired frequencies, and 'alternating'current conductive paths of lovv impedance for impulses of undesired 1 frequencies interconnecting the plate circuits of said amplifiers n 19. Analternating current system comprising` a number of electric discharge devices having their respective electrodes connected in parallel, one corresponding set of said electrodes being connected toy a common busbar by leads provided'vvith means forconducting currents of desired frequencies, and for blocking currents Vof other frequencies, and suppressing paths for said other frequencies associated with said set of electrodes.

2O;V In a system comprising a number of electric discharge deviceshaving circuits connecting their corresponding electrodes in parallel, meansassociated with each of said circuits for suppressing undesiredoscillations and each includingapathof lovv impedance for oscillationsv of desired frequency but of high impedance for undesired oscillations and a path ofloiv'impeda'nce for undesired oscillations including means for suppressing said undesired oscillations, and .paths lof low impedance for other undesired oscillations including means for suppressing said other oscillations.

2l. In a system lcomprisinga number of electric discharge devices v.having circuits connecting their grids and plates in parallel, a network associated withv the grid circuit, a network associated With the plate circuit, each network including a path of low imped- 'auce for oscillations of desired frequencies,

which is 'of high impedance for undesired oscillations,.and a path of lou7 impedance for indesired oscillations including means forlissipating the energy of said undesired oscil- .ations ,22. Ina system comprising a number of alectric discharge devicesv having circuits zonnecting their grids and vplates in-pa-rallel, inetwork associatedy with the grid; circuit, a letworklfassociated withv the plate circuit, each network including a path of lowimpedince for desired oscillationsy which iso-f high Y Lmpedance for vundesired oscillations, means isso'ciated with said path for suppressing unV- desired oscillations, and a path of low impedance for other undesired oscillations in- V:luding means for suppressing said other os- :illatio-ns. y v 23. A space discharge system comprising a plurality of units and meansconnecting said units in parallel relation'to an external cir-j cuit,.said means consisting of a low impedance path for desired "oscillations andv at least one other path conductive for undesired oscillations in which saidundesired oscillationsare suppressed. e l e i e 24. A' space discharge system comprising a plurality ofy space discharge; 'units, Vmeans, consisting vof apath of low impedance for Waves'of desired frequency and other impedance lfor waves of undesired frequencies for `connecting said units in parallel relation with the generation of spurious oscillations is prevented.

` 29. A system comprising aiplurality of ,i

units, each unit including at least one space discharge device having an anode, and a control electrode, and paths connecting certain of the corresponding electrodes of said devices, said paths including inductance Vand resistance elements in parallel. i

30. In asystem in accordance with claim 29, additional reslstancesv connecting corresponding electrodes of certain of said de-V vices.

31. In a system comprising a number of space discharge units connected in parallel relation, aV bus-bar conductor to which` corresponding electrodes of said devices are connected by leads each of which includesv a resistance and inductance element in parallel.`

In witness whereof, I hereunto subscribe' 17th day of May, 1923. Y J OI-IN C. SCHELLENG. In Witness whereof, I hereunto subscribe my name this 27th day of April, 1923.

Y ARTHUR A. OSWALD.

my name this respect to an external circuit andV tocontrol 'Y the suppression ofl said undesired wayes.

25. `A space discharge system comprising a.

plurality of space discharge units, means consistingvofalow impedance path for desired oscillations anda high impedance for funde-v sired oscillations for connectingsaid units in parallel relationf with respect to an external circuit and to control the suppression of un- Y desired oscillations. f 26.' A space discharge system comprising ka plurality vof 'space discharge units', ymeans for connecting said' units in parallel'y relation withrespect to an external circuit, said means comprising a path of low impedance for oscils lations of desired frequency but of high impedance for undesired oscillations, and a means for suppressing said kundesired oscil- [ations associated withk said connecting means.

- 27. JA' space discharge system comprising a plurality of space discharge units, means for connecting said units in parallel relation with l y respectto an external circuit, said meanscomprsing a, ath of low impedance for oscillationsg'of'Y esired frequency but lofhigh im-v pedance for undesired oscillationsand means i in'para'llel with `said connectingfmeans forV suppressing said desiredoscillations.` y

"28.A systemY comprisingv a plurality of units, each including at least oner space discharge device, ysaid units. being connected in parallel-,an input circuit andv an, outputcirx cuit therefor, and a network,supplementaryrr to'v said circuits,including resistive paths be tween one'unt and each other unitwhereby Y 

